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Latest blog entry: My 2012 FPV year in Review
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Just curious but I would think the wings would be completely ineffective until you got back down to a level where the air was thick enough.
http://en.wikipedia.org/wiki/Project_Excelsior I remember reading somewhere the guy saying it was eerily quiet and not feeling any wind despite reaching nearly 1000 Kph at one stage Just remembered this article from last year. http://www.metro.co.uk/news/818988-a...sing-a-balloon Nick |
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The U2 cruised at 70k feet, not 100k feet.
It was forced to fly near its maximum airspeed to stay up there, which at that altitude is only 10 knots above its stall speed. It was constantly riding a very fine line between going too fast and ripping the wings off, and stalling and simply falling out of the sky. The SR-71's two engines generated over 64 thousand pounds of thrust, and cruising at Mach 3ish it could overcome the low air density and very high stall speed at 80-100k feet. An R/C aircraft dropped from 100k feet, won't even know which direction to point into the wind for 30-40k feet of free fall and likely wouldn't actually be able to make any meaningful direction changes until it drops below about 50k feet. Neither is really a big deal though. As long as you don't over control it too early, a flying wing with big winglets will naturally point its nose down when it can. It may be falling at several hundred mph, but air pressure will only generate airspeed equivalent of 150-200mph before drag builds enough to start slowing down again. Building foamie airframes that can take that is not a huge challenge. The bigger challenges are temperature regulation, and maintaining control and video at the extreme ranges that the plane is likely to blow downwind with the balloon during ascent. If you ignore those and simply autopilot home, then I don't much see the point. There's already a company doing that with an autonomous model aircraft. ian |
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Latest blog entry: My 2012 FPV year in Review
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